JP2014011565A - Camera module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera module which has excellent shielding property and is reduced in lens distortion caused by heat.SOLUTION: A camera module 1 comprises: a case 2; a lens 3 held by the case 2; an imaging device 4 disposed within the case 2 so as to face the lens 3; a circuit board 5 which supports the imaging device 4; and a shield member 6 connected to the circuit board 5 so as to surround the imaging device 4 and the circuit board 5. The shield member 6 comprises: a first shield member 6a positioned on the lens 3 side of the circuit board 5; and a second shield member 6b positioned on the opposite side of the circuit board 5 from the lens 3. The first shield member 6a is smaller in heat conductivity than the second shield member 6b.

Description

  The present invention relates to a camera module used in, for example, an in-vehicle camera or a security camera.

  In recent years, a camera has been attached to the rear of an automobile in order to confirm the safety behind the automobile. As such a camera module for an in-vehicle camera, an image sensor is arranged in the case so as to face the lens held in the case, and a shield member is arranged so as to surround the image sensor for shielding. (For example, see Patent Document 1). The shield member is connected to a circuit board on which the image sensor is mounted, and has a cylindrical shape extending from the image sensor to the lens side and the opposite side of the lens, thereby surrounding the image sensor.

JP 2011-259101 A

  However, in the conventional camera module, the shield member also serves as a heat conducting member for conducting heat generated in the image sensor to the outside. Therefore, the heat generated in the image sensor is conducted to the shield member through the circuit board and is conducted from the image sensor to the lens side. At this time, since heat is radiated from the end of the shield member on the lens side, the lens is distorted by the radiant heat, and there is a problem that an image captured by the camera module is distorted.

  A camera module according to one embodiment of the present invention includes a case, a lens held in the case, an image sensor disposed in the case so as to face the lens, a circuit board that supports the image sensor, an image sensor, A shield member connected to the circuit board so as to surround the circuit board, the shield member extending from the circuit board to the lens side and the first shield member opposite to the lens The first shield member has a lower thermal conductivity than the second shield member.

  According to the camera module of one aspect of the present invention, the shield member is located on the lens side of the circuit board, and the second shield member extends from the first shield member to the opposite side of the lens. Since the first shield member has a lower thermal conductivity than the second shield member, the heat generated in the image sensor is conducted toward the second shield member having a higher thermal conductivity. The radiant heat from the first shield member that is close is reduced, and the distortion of the lens due to the radiant heat is reduced.

(A) is a perspective view which shows the external appearance of the camera module which concerns on embodiment of this invention, (b) is a disassembled perspective view. (A) is sectional drawing in AA of Fig.1 (a), (b) is sectional drawing in AA of (a). (A) is sectional drawing which shows the modification of the camera module shown by Fig.2 (a), (b) is sectional drawing in AA of (a). It is sectional drawing which expands and shows the A section of Fig.3 (a).

  Hereinafter, a camera module according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

  FIG. 1A is a perspective view showing an appearance of a camera module 1 according to an embodiment of the present invention, and FIG. 1B is an exploded perspective view. 2A is a cross-sectional view taken along the line AA in FIG. 1A, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. The camera module 1 may have either direction upward or downward. For convenience, the camera module 1 defines an orthogonal coordinate system xyz, and the upper side or lower surface is defined with the positive side in the z direction as the upper side. Words shall be used.

  The camera module 1 mainly includes a case 2, a lens 3 held in the case 2, an image sensor 4 disposed in the case 2 so as to face the lens 3, and a circuit board 5 that supports the image sensor 4. The image sensor 4 and the circuit board 5 are surrounded by the shield member 6 connected to the circuit board 5.

  The case 2 is for holding the lens 3 and accommodating the imaging device 4, the circuit board 5, and the shield member 6. The case 2 has an opening at the end, and the lens 3 is fixed to the end so that light from the outside is condensed and taken into the case 2. In the camera module 1 shown in FIGS. 1 and 2, the case 2 has an opening for taking in light from the outside, the first case 2 a to which the lens 3 is fixed, the imaging device 4, and the circuit board. 5 and the second case 2b in which the shield member 6 is accommodated. The second case 2b has an opening through which the cable 7 is inserted. The first case 2a and the second case 2b are coupled by screwing with a screw 21 with a packing (not shown) interposed therebetween, for example. Or the 1st case 2a and the 2nd case 2b may be couple | bonded by the adhesive agent and welding. In the case of bonding by an adhesive or welding, gas may be generated from the adhesive or welding portion and adhere to the lens 3, so that bonding by screwing is preferable.

  Case 2 consists of sulfone resin (polysulfone (PSF), polyethersulfone (PESF), polyphenyl sulfide (PPE)), polyphthalamide resin (PPA), polycarbonate (PC), acrylonitrile-butadiene-styrene. It consists of resin such as polymerized synthetic resin (ABS). When the camera module 1 is used in a vehicle, it is preferable to use PPA that is excellent in strength and heat resistance, and has both dimensional stability and chemical resistance.

  As the lens 3, a glass lens, a plastic lens, or a hybrid lens of these composite types can be used. When a plastic lens is used, the lens 3 can be easily molded by a mold, and the shape is highly optional, and there are advantages such as a large cost merit over a glass lens. If necessary, an optical film such as an AR coat (Anti-Reflective coat) may be formed on the surface of the lens 3. In the example shown in FIG. 2, the lens 3 is a single convex lens, but it may be composed of a plurality of convex lenses or concave lenses.

  In the example shown in FIG. 2, the lens 3 is fixed to the case 2 (first case 2a) by fixing the outer periphery of the lens 3 by the inner periphery of the opening of the first case 2a. A step portion may be provided on the inner wall surface, and the lens 3 may be pressed against the step portion with a pressing member and fixed.

The image sensor 4 is a CCD (Charge Coupled Device) image sensor or C
A solid-state imaging device such as a MOS (Complementary Metal Oxide Semiconductor) image sensor may be used. If the camera module 1 is used for an in-vehicle camera, for example, an image sensor 4 with 300,000 to 5,000,000 pixels may be used. The image sensor 4 is mounted on the circuit board 5 with the light receiving portion 41 facing the lens 3.

  As the circuit board 5, for example, a so-called printed wiring board in which wiring made of copper is formed using an epoxy resin as a base material is used. By joining the electrode formed on the upper surface of the circuit board 5 and the terminal electrode of the image sensor 4 with a conductive bonding material, the image sensor 4 is electrically connected to the circuit board 5 and mechanically fixed. Is done. On the upper and lower surfaces of the circuit board 5, electronic components constituting an electronic circuit other than the image sensor 4 may be mounted. For example, an IC (not shown) that processes an electrical signal output from the image sensor 4, wiring of the circuit board 5 and an external circuit (for example, an automotive ECU in which a camera is mounted in the case of an in-vehicle camera) A connector (not shown) for connecting a cable 7 for electrically connecting the two or a passive component such as a capacitor is mounted.

  The circuit board 5 is fixed to the first case 2a with screws (not shown), for example. The positional relationship between the lens 3 and the image sensor 4 is fixed by being fixed to the first case 2a. At this time, if a spacer is provided between the circuit board 5 and the first case 2a, the setting of the distance between the lens 3 and the image sensor 4 and the adjustment of the optical axis can be facilitated.

  The shield member 6 has a shielding effect for preventing electromagnetic waves from being emitted from the electronic circuit on the circuit board 5 to the surroundings, and preventing the influence of electromagnetic waves from the surroundings to the electronic circuit. Are connected to each other to radiate heat generated in the image pickup element 4 and the IC element via the circuit board 5. In order to enhance the shielding effect, it is preferable to be electrically connected to the ground wiring formed on the circuit board 5. In the camera module 1 shown in FIG. 1 and FIG. 2, a hook-like connection portion 6c extending inward from a main body portion surrounding the circuit board 5 of the shield member 6 is provided. A ground wiring 5 a on the upper surface of the circuit board 5 is connected. For the connection, a conductive bonding material such as solder or conductive resin may be used.

  3A is a cross-sectional view showing a modification of the camera module 1 shown in FIG. 2A, and FIG. 3B is a cross-sectional view taken along line AA of FIG. 3A. FIG. 4 is an enlarged cross-sectional view of a portion A in FIG. 3 and 4 is different from the camera module 1 shown in FIGS. 1 and 2 in the shape of the shield member 6.

In the camera module 1 shown in FIGS. 1 and 2, the shape of the shield member 6 is a cylindrical body that surrounds the circuit board 5, and is above (on the lens 3 side) and below (the cable 7) the shield member 6. Side) is open. On the other hand, in the camera module 1 shown in FIG. 3, the end of the shield member 6 on the side of the lens 3 has an entire circumference so as to partition the space between the lens 3, the image sensor 4 and the circuit board 5. It extends over the inside, and has a shape that closes a part of the end of the cylindrical body on the lens 3 side. With such a shape, not only the shielding effect in the direction of the lens 3 is improved, but also the shielding member 6 functions as a heat shield that blocks the radiant heat from the image sensor 4 toward the lens 3. This is preferable because the distortion of the lens 3 due to the above can be further reduced. This means that the end of the shield member 6 on the lens 3 side has a shielding plate 6d against electromagnetic waves and heat. The shielding plate 6d is provided with a window (opening) 61 at the center when viewed from the lens 3 side, and only a part of the end of the shielding member 6 on the lens 3 side is closed. This is because the light that has entered through the lens 3 from the outside is not blocked, and is input to the light receiving unit 41 of the image sensor 4 as an optical signal. The size of the window 61 is slightly larger than the size of the light receiving part 41 of the image sensor 4 and may be set according to the size of the light receiving part 41. Although the window 61 in the camera module 1 shown in FIG. 3 is an opening, a translucent member may be disposed in the window 61.

  The shield member 6 only needs to have conductivity, such as a metal such as aluminum, copper, iron, brass, a conductive resin in which metal particles are dispersed inside, a resin having a metal film 62 formed on the surface, or the like. A resin containing a resin and a metal can be used. When the shield member 6 is made of a material containing resin and metal, the resin may be the same as that of the case 2, and the metal such as the metal particles and the metal film 62 may be aluminum, copper, iron, brass, etc. May be used.

  The shield member 6 includes a first shield member 6 a located on the lens 3 side from the circuit board 5 and a second shield member 6 b extending from the first shield member 6 a to the opposite side of the lens 3. The first shield member 6a has a lower thermal conductivity than the second shield member 6b. Since the shield member 6 having such a configuration is provided, the camera module 1 conducts heat generated in the imaging device 4 and the like toward the second shield member 6b having a high thermal conductivity. The radiant heat from the first shield member 6a is reduced, and the distortion of the lens 3 due to the radiant heat is reduced.

  Both the first shield member 6a and the second shield member 6b are made of the metal as described above, and it is sufficient that the thermal conductivity of the first shield member 6a is smaller than the thermal conductivity of the second shield member 6b. In order to further reduce the radiant heat from the first shield member 6a, the difference in thermal conductivity may be increased. It is preferable that the first shield member 6a includes resin and metal, and the second shield member 6b is made of metal.

  When the first shield member 6a includes a resin and a metal, as described above, for example, a conductive resin in which metal particles are dispersed inside the resin or a resin in which the metal film 62 is formed on the surface can be given. Since the resin having the metal film 62 formed on the surface is easier to increase the resin ratio, the thermal conductivity of the first shield member 6a can be further reduced. The metal film 62 can be formed on the surface of a resinous member by a thin film forming method such as vapor deposition of a metal such as aluminum, gold, silver, or copper.

  In the case where the first shield member 6a has the metal film 62 on the surface, the metal film 62 is preferably formed on the inner surface of the resinous member. When the metal film 62 is formed on the inner surface of the first shield member 6a, the heat generated in the image pickup device 4 passes through the metal film 62 having better thermal conductivity than that of the resin, and the second shield member 6b. It is because it is easy to conduct to the direction.

  In the camera module 1 shown in FIG. 4, the first shield member 6a is provided with a shielding plate portion 6d, and the metal film 62 is the second shield member 6b at the end on the second shield member 6b side. Is extended to the periphery of the window 61 on the inner surface of the shielding plate 6d. Thus, when the first shield member 6a has the shielding plate portion 6d, the heat generated in the imaging element 4 is not only easily conducted to the second shield member 6b through the metal film 62, Since the light is reflected by the metal film 62 on the surface (inner surface) of the shielding plate portion 6d on the imaging element 4 side, it becomes easier to conduct toward the second shield member 6b. Further, the surface (outer surface) on the lens 3 side of the shielding plate portion 6d is resin, and the surface from the outer surface of the first shield member 6a to the lens 3 side is compared with the case where the metal film 62 is formed on the outer surface. Radiant heat can be further reduced.

Since the thermal conductivity of the second shield member 6b is larger than the thermal conductivity of the first shield member 6a, the thermal connection between the shield member 6 and the circuit board 5 is made by the second shield member 6b. Good. In the camera module 1 shown in FIGS. 1 to 4, the second shield member 6 b
A connecting portion 6 c is provided at the end of the lens 3 side and is connected to the ground wiring 5 a on the upper surface of the circuit board 5.

  Further, the first shield member 6a and the second shield member 6b are not only thermally connected but also electrically connected. In the camera module 1 shown in FIG. 4, the metal film 62 is formed on the inner surface of the first shield member 6a, and the outer surface of the metal second shield member 6b is the metal film 62 of the first shield member 6a. The second shield member 6b is fitted into the first shield member 6a so as to be in contact with the first shield member 6a. In order to make electrical and thermal connection more reliable, a conductive bonding material may be used.

  It is preferable to thermally connect the shield member 6b to the case 2 so as to dissipate heat to the outside of the camera module 1 via the case 2. In this case, it is preferable to suppress heat transfer to the lens 3 by connecting the second shield member 6b and the second case 2b. If the first case 2a and the second case 2b are connected to the screw 21 for coupling, the heat can be radiated to the outside more efficiently. Further, if the thermal conductivity of the packing sandwiched between the first case 2a and the second case 2b is smaller than the thermal conductivity of the case 2 (second case 2b), the second case 2b To the first case 2a can be further reduced. For example, when PPA is used as the material of the case 2, ethylene propylene may be used for the packing.

  In the camera module 1 shown in FIGS. 1 to 4, a cover 8 for protecting the lens 3 is disposed outside the lens 3. The cover 8 is made of glass, and an optical film such as an AR coat may be formed as necessary. As described above, the cover 8 is not necessarily required because the lens 3 may be composed of a plurality of lenses or an optical film may be formed on the lens 3.

1: Camera module 2: Case 2a: First case 2b: Second case 3: Lens 4: Image sensor 5: Circuit board 6: Shield member 6a: First shield member 6b: First shield member 7: Cable 8: Cover

Claims (2)

Case and
A lens supported by the case;
An image sensor disposed in the case so as to face the lens;
A circuit board that supports the imaging device;
A shield member surrounding the imaging element and the circuit board and connected to the circuit board,
The shield member includes a first shield member located on the lens side from the circuit board, and a second shield member extending from the first shield member to the opposite side of the lens, and The camera module according to claim 1, wherein the first shield member has a lower thermal conductivity than the second shield member.   The camera module according to claim 1, wherein the first shield member includes a resin and a metal, and the second shield member is formed of a metal.

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